This study contributes to the limited research on teacher agency in task-based language teaching. Conceptualising agency through the lens of activity theory, the study investigated how two EFL teachers enacted their agency in TBLT implementation at a Chinese university and what factors mediated the enactment of their agency. Data collected by means of classroom observation, interviews and course documents were triangulated to provide a descriptive synthesis of teacher participants’ experiences with task-based language teaching. The analysis of the data revealed that these two teachers demonstrated agency through teaching as adaptation and teaching as learning to overcome the contradictions in the instructional activity system. They engaged with both proactive and reactive agency. A number of mediational factors were found to account for their agency. The study highlights the crucial role of teachers’ shared beliefs on the value of TBLT and curriculum reform and institutional support in influencing teachers’ adoption of task-supported language teaching.

This study is aimed to identify the effects of task complexity on first language (L1) use and the functions it may serve when two groups of learners of English as a foreign language (EFL) work on collaborative tasks. Twenty-four pairs of Chinese EFL learners from two universities were assigned to a lower-proficiency and a higher-proficiency group, each with twelve pairs. Each group completed two collaborative tasks of different cognitive complexity. The results showed that task complexity had an appreciable impact on the use of L1 and its functions. It is also found that the impact of task complexity was dependent on learners’ English proficiency. Specifically, the higher-proficiency group employed more L1 to perform complex tasks than they did in the simple versions of the tasks. These learners also devoted significantly more L1 turns to fulfill the functions of metacognitive and grammar talk to complete the complex tasks. These trends did not hold for the lower-proficiency group.